What is the area between the end of a file's logical size and the file's physical size called?

The area between the end of a file's logical size and the file's physical size is referred to as slack space. This term captures the concept that files, when written to disk, often do not completely fill the last sector or cluster allocated to them. For example, if a file occupies 3.5 sectors, the space in the fourth sector that is not utilized by the file data constitutes the slack space.

This slack space can contain remnants of previous data that was stored in that location before the new data was written, making it potentially valuable for forensic examination because it may contain fragments of deleted files or other sensitive information. The concept emphasizes the importance of understanding how data is stored and the implications for data recovery and forensic investigations.

The other terms listed refer to different concepts. Unused disk area refers to space on the disk that is not allocated to any files. Unallocated clusters or sectors refer to portions of the disk that are not currently being used by any data or files. While they are relevant in the context of disk management and data recovery, they do not specifically explain the phenomenon that occurs due to the differences in file logical and physical sizes, which is characterized by slack space.